Piano by the Numbers
A standard piano has 88 keys — 52 white and 36 black — spanning just over seven octaves from A0 (27.5 Hz) to C8 (about 4,186 Hz), with 12 notes in each octave. Below are the key facts and figures about the instrument and the music theory behind it, alongside the size of this site’s reference library.
Figures reflect a standard 88-key piano and piano.org’s reference corpus. Last reviewed July 2026.
The instrument
The keyboard, its range, and how it’s tuned.
A standard acoustic or full-size digital piano has 88 keys, spanning A0 to C8.
The white keys play the seven natural notes (A–G) repeated across the keyboard.
The black keys play the five sharps and flats in each octave, grouped in twos and threes.
Western music divides each octave into 12 equal semitones — 7 white and 5 black keys.
The 88-key range covers just over seven octaves, from the lowest A to the highest C.
The lowest key (A0) sounds at 27.5 Hz; the highest (C8) at about 4,186 Hz.
Most notes use three strings; the lowest use two or one, for roughly 230 strings in total.
Pianos are typically tuned so the A above middle C sounds at 440 Hz (A440).
The theory
How many chords, scales, modes, and keys there are to learn.
We cover all 18 written keys — both enharmonic spellings, e.g. C♯ and D♭, each on its own page.
From triads and sevenths to extended, altered, suspended, and added-note chords.
Major, minor (natural, harmonic, melodic), pentatonic, blues, and exotic scales — each in every key.
Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, and Locrian.
From unison to the octave, each interval has a name and a characteristic sound.
The reference library
What piano.org documents, page for page.
43 chord types across 18 keys, each with notes, fingering, inversions, and a playable keyboard.
The seven modes in all 18 keys, each with its own notes, character, and interactive diagram.
Chords, scales, modes, theory lessons, and interactive tools, all with no login required.